1. Field of the Invention
This invention relates to water treatment systems and, in particular, to systems and methods for dewatering and thickening operations within water treatment systems.
2. Description of the Related Art
During the treatment of water or wastewater, a residuals stream arising from, for example, a water treatment plant, a wastewater facility or an industrial process, may be dewatered or thickened to, for example, reduce the volume of liquid waste, or to produce a more solid waste for landfill. The residuals stream may be separated into a liquid-rich stream and a solid-rich (“cake”) stream. The cake stream may be converted into fertilizer, or otherwise disposed of. The liquid-rich stream may also be referred to as a “centrate” or a “filtrate,” depending on the separation technique used, in reference to centrifuges and filters, respectively. In some cases, a treatment agent may be added, for example, to promote aggregation of solid material for easier handling, separation, or disposal. The optimal amount of treatment agent may be a function of the solids content.
Techniques for adding treatment agent to a residuals stream have previously been disclosed in, for example, U.S. Pat. No. 5,620,609 by Field; U.S. Pat. No. 5,382,356 by Thogho et al.; Papavasilopoulos et al., Wat. Sci. Tech., 38:33-40 (1998); Dentel et al., Wat. Res., 79:2663-2672 (1995); or Abu-Orf et al., Water Environment Federation, 67 Annual Conference & Exposition, Chicago, Ill. (1994). Another system to add treatment agent to a residuals stream has been disclosed in U.S. Pat. No. 5,645,799 by Shah et al.